Yes, extensive, or numerous CMN is considered as a rare disease as it effects 1 in 10-20,000 births.
As a rare disease, Congenital Melanocytic Naevi (CMN) has many different expressions which lead to differing experiences for those affected. For some CMN is found solely on the skin as a dark brown birthmark covering up to 80% of the body and in varying forms, such as flat, raised, lumpy, hairy, itchy and fragile. Raised and lumpy CMN can be limiting for our members, affecting mobility, and often affecting sleep due to itch. There is also a small increase in the risk of developing melanoma when CMN is present on the skin.
However, CMN can also affect body systems beyond the skin, causing neurological problems and medical complexities, which in the worst cases can be fatal. These experiences are not exclusive to one another e.g. someone with raised, lumpy CMN could also experience neurological complications. What is key to remember, as a mosaic disorder, CMN must be present on the skin if it is to be present internally.
You can read more about the experiences of CMN here.
